proportional representation

...and European Parliament elections in Northern Ireland. Under STV, voters rank candidates on the ballot in order of preference. In the 1860s Henry Richmond Droop developed a quota (the so-called
Droop quota) to determine the number of votes a candidate needed to capture to win election under STV. The quota is calculated by dividing the total number of valid votes cast by the number of seats...

single transferable vote

...one of its English developers, Thomas Hare—employs a ballot that allows the voter to rank candidates in order of preference. In the 1860s Henry Richmond Droop developed a quota (the so-called
Droop quota) to determine the number of votes a candidate needed to capture to win election under STV. The quota is calculated by dividing the total number of valid votes cast by the number of seats...